objtool: Support Clang non-section symbols in ORC dump

Historically, the relocation symbols for ORC entries have only been
section symbols:

  .text+0: sp:sp+8 bp:(und) type:call end:0

However, the Clang assembler is aggressive about stripping section
symbols.  In that case we will need to use function symbols:

  freezing_slow_path+0: sp:sp+8 bp:(und) type:call end:0

In preparation for the generation of such entries in "objtool orc
generate", add support for reading them in "objtool orc dump".

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/b811b5eb1a42602c3b523576dc5efab9ad1c174d.1585761021.git.jpoimboe@redhat.com

diff --git a/tools/objtool/orc_dump.c b/tools/objtool/orc_dump.c
index 13ccf77..ba4cbb1 100644 (file)
--- a/tools/objtool/orc_dump.c
+++ b/tools/objtool/orc_dump.c
@@ -66,7 +66,7 @@ int orc_dump(const char *_objname)
        char *name;
        size_t nr_sections;
        Elf64_Addr orc_ip_addr = 0;
-       size_t shstrtab_idx;
+       size_t shstrtab_idx, strtab_idx = 0;
        Elf *elf;
        Elf_Scn *scn;
        GElf_Shdr sh;
@@ -127,6 +127,8 @@ int orc_dump(const char *_objname)
 
                if (!strcmp(name, ".symtab")) {
                        symtab = data;
+               } else if (!strcmp(name, ".strtab")) {
+                       strtab_idx = i;
                } else if (!strcmp(name, ".orc_unwind")) {
                        orc = data->d_buf;
                        orc_size = sh.sh_size;
@@ -138,7 +140,7 @@ int orc_dump(const char *_objname)
                }
        }
 
-       if (!symtab || !orc || !orc_ip)
+       if (!symtab || !strtab_idx || !orc || !orc_ip)
                return 0;
 
        if (orc_size % sizeof(*orc) != 0) {
@@ -159,21 +161,29 @@ int orc_dump(const char *_objname)
                                return -1;
                        }
 
-                       scn = elf_getscn(elf, sym.st_shndx);
-                       if (!scn) {
-                               WARN_ELF("elf_getscn");
-                               return -1;
-                       }
-
-                       if (!gelf_getshdr(scn, &sh)) {
-                               WARN_ELF("gelf_getshdr");
-                               return -1;
-                       }
-
-                       name = elf_strptr(elf, shstrtab_idx, sh.sh_name);
-                       if (!name || !*name) {
-                               WARN_ELF("elf_strptr");
-                               return -1;
+                       if (GELF_ST_TYPE(sym.st_info) == STT_SECTION) {
+                               scn = elf_getscn(elf, sym.st_shndx);
+                               if (!scn) {
+                                       WARN_ELF("elf_getscn");
+                                       return -1;
+                               }
+
+                               if (!gelf_getshdr(scn, &sh)) {
+                                       WARN_ELF("gelf_getshdr");
+                                       return -1;
+                               }
+
+                               name = elf_strptr(elf, shstrtab_idx, sh.sh_name);
+                               if (!name) {
+                                       WARN_ELF("elf_strptr");
+                                       return -1;
+                               }
+                       } else {
+                               name = elf_strptr(elf, strtab_idx, sym.st_name);
+                               if (!name) {
+                                       WARN_ELF("elf_strptr");
+                                       return -1;
+                               }
                        }
 
                        printf("%s+%llx:", name, (unsigned long long)rela.r_addend);